Something

sub f ($) {
	my $x = shift;
	return sqrt(abs($x) + 5*($x**3));
}

my @a;
$a[$_] = <> for (0..10);

for (my $i = @a; $i >= 0; $i--) {
	my $y = f($a[$i]);
	print "$i too large\n" if $y > 400;
	print "$i: $y\n" unless $y > 400;
}